My tIVo failed, and while trying to diagnose, I removed watch battery on motherboard. That didn't fix it (still stuck on welcome), so I purchased another unit, same model.

After confirming new TiVo worked, I put drive for my original T in replacement. Same problem, although this time it got stuck on Almost There screen.

I then put drive from replacement T in original (lifetime) unit. After a couple tries, it booted into main play list menu. Yoppee!! However, several things popped out immediately;
1. OS on replacement drive is so old, it's missing 1 or 2 of the main menu items. I can't remember which, but it's only showing 4 choices.
2. Evidently, OS is so old it won't recognize the USB ports on my motherboard, so I can't connect to TiVo service. And, since all telephone lines in neighborhood are digital, it can't talk to TiVo using a phone line.
3. Finally, it appears that the watch battery ihad nothing to do with retaining instead of retaining at least some of the network and config settings, but it did keep the media key!

So, here are my questions;
A. Do I need the media key, and other now missing system info, that I lost when I removed the watch battery, to access my lifetime service, or is the needed sn or ID part of the firmware? I can't see any sign of an sn or eid anywhere.
2. Is there a way to upgrade the OS on this drive without using a network or phone connection?

I know I have to eventually get an upgraded drive (the one that faled was only @18 mo old! The original lasted 8 years!), but befor investing in that I want to make sure all the other equip is still working - mainly network adaptor, IR blaster, downloading from TiVo service, etc.

You can do serial PPP. With one of the earliest supported wired Ethernet adapters, the ,#401 code might work.

You could buy Instantcake, or beg for an image for your model in the image thread in the upgrade forum.

The coin cell holds only the time (as in keeps a clock runnung).

The ID off the TiVo is held on a non-volatile crypto chip, which the HDD is married to (error 51 indicates a mismatch - a C&DE fixes that). Your PL account status and MAK is on TiVo's servers, which your TiVo retrieves in its call. All local settings, apart from the time, are held on the HDD.

__________________
Series 2 234 Hr Lifetime.
Window XP and Ubuntu Linux on my PCs.
Watching more and more in HD direct now.

That raises the question, then, as to why the TiVo (Series 2) Is telling me I have to activate it, and that it doesn't know the media key. Its been activated for 10 years. It specifically says media key unknown, and lists all zeros for it.

Checking System Info shows most of that information has been wiped, zeroes or <unknown> instead of "real" data.

",#401" (that's comma pound four zero one) in the dial prefix field tells the TiVo to make the connection via the Net rather than dial-up. I have a couple of TiVo 2s that have never been connected to a phone line.

My tIVo failed, and while trying to diagnose, I removed watch battery on motherboard. That didn't fix it (still stuck on welcome), so I purchased another unit, same model.

After confirming new TiVo worked, I put drive for my original T in replacement. Same problem, although this time it got stuck on Almost There screen.

I then put drive from replacement T in original (lifetime) unit. After a couple tries, it booted into main play list menu. Yoppee!! However, several things popped out immediately;
1. OS on replacement drive is so old, it's missing 1 or 2 of the main menu items. I can't remember which, but it's only showing 4 choices.
2. Evidently, OS is so old it won't recognize the USB ports on my motherboard, so I can't connect to TiVo service. And, since all telephone lines in neighborhood are digital, it can't talk to TiVo using a phone line.
3. Finally, it appears that the watch battery ihad nothing to do with retaining instead of retaining at least some of the network and config settings, but it did keep the media key!

So, here are my questions;
A. Do I need the media key, and other now missing system info, that I lost when I removed the watch battery, to access my lifetime service, or is the needed sn or ID part of the firmware? I can't see any sign of an sn or eid anywhere.
2. Is there a way to upgrade the OS on this drive without using a network or phone connection?

I know I have to eventually get an upgraded drive (the one that faled was only @18 mo old! The original lasted 8 years!), but befor investing in that I want to make sure all the other equip is still working - mainly network adaptor, IR blaster, downloading from TiVo service, etc.

Thanks in advance

What's the model number of that TiVo?

What size is the drive that was in when it started giving trouble?

What size is the drive that was in that second TiVo which you just bought?